Prepaid Monthly Calling System

/*Here is a program for a post paid customer .where every call cost is 1.25 tk.its a fully postpaid calling system where customer have a monthly limit but he can use how much he want to use. */

#include<stdio.h>

void main()

{

    float rbill=0,blnc,time,tmp_time=0;

    char ch;

    printf("Enter your monthly postpaid limit in taka: ");

    scanf("%f", &blnc);

    loop:

        {

            do

    {

        printf("\n\n");

        printf("Press for a call...");

        getch();

        printf("\nEnter your call time: ");

        scanf("%f", &tmp_time);

        time+=tmp_time;

        rbill+=(tmp_time*1.25);

        printf("Your total call time: %.2f minute.\nYour total bill: %.2f taka.",time,rbill);

    }while(rbill<blnc);

    printf("\n\nSorry You Have Crossed Your Monthly Limit.\nYou have used %.2f extra balance from your limit\n\n", (rbill-blnc));

    printf("If you still want to call press 'c' or 'C' key or Any key to end : ");

    scanf("%s", &ch);

    if(ch=='c'||ch=='C')

    {

        goto loop;

    }

    else

    {

        printf("Program end.");

    }

        }

}